An Tzu Yang at 80

Dr. An Tzu Yang, known as Andy, who developed a geometric theory for broad use, died on
Nov. 21 in Woodland, Calif. He was 80.

Dr. Yang was born in Shanghai, China, Oct 5, 1923. He fled the Japanese-occupied province in
1942 for the ancient city of Xian in northwest China. Living in a mud shack with no electricity, he
earned his bachelor's degree from the Northwestern College of Engineering, a school for refugees
in Xian. Dr. Yang immigrated to the United States in 1949 and earned a master's degree at Ohio
State University and a doctorate at Columbia. His doctoral dissertation is often credited with
modernizing the theory of screws that uses geometry to explain the forces acting on any solid
object, like a car, as it moves through space. Today, it is one of the most heavily cited papers in
its field. He retired in 1991. Throughout his career he won many awards and was a member of
several scientific organizations, including the New York Academy of Sciences.

He is survived by his wife of 50 years and two sons, Eton Y., of Davis, Calif., and Yuelin T., of
Singapore. (Source: Anahad O'Connor, The New York Times, Dec. 8, 2003; Bowker
Biographical Dictionary).